The author has investigated teacher and parent assessments of students' mental health based upon data from the evaluation of KidsMatter, the Australian mental health promotion, prevention and early intervention initiative. She notes that the prevalence of child and adolescent mental health disorders has increased over the last 50 years, according to investigators, to the extent that it is now of major concern in Australia. In order to counter this trend, national initiatives, such as KidsMatter, have been trialled with the intention of improving the mental health outcomes for Australian primary school children. The author discusses the use of multiple instruments from multiple informants and the challenge of classifying each child's mental health status by bringing these various assessments together. A technique called latent class analysis was considered to be the best approach and is the focus of the chapter. [Author abstract, ed]